The type of riding you plan to do will determine the style of bike you choose, which in turn will dictate the frame size and components you will need. The most important part of buying a bike is finding one that fits you.

Frame size is not dependent on your overall height. Rather, it is more a matter of leg length. Here are some starting points to help you determine if a particular bike is within your size range.

Frame height

Generally speaking, when sizing a diamond frame bike, sometimes called a men's or unisex frame, you need to measure how it will fit when you straddle the cross bar while flat-footed in the shoes you'll be riding in. So measure your inseam from the bottom of your feet to your crotch.

For a road or hybrid bike, you should have an inch or two of clearance between your crotch and the top tube

For a mountain bike, clearance should be about four inches--especially if you'll be riding in rugged terrain where an unplanned dismount is likely

BMX and freestyle bikes all have 20-inch wheels, so frame size isn't really an issue. A rider's physique and riding style is accommodated by choosing the appropriate seatpost, stem, handlebar and crankarm lengths.

When considering a women's frame, or frame with no cross bar, clearance isn't an issue. In this case, the best fit is usually determined by reach.

Frame sizes come in inches or centimeters, depending on the manufacturer

Not all manufacturers measure from the same points on the frame. Some measure from the bottom of the crankset to the top of the seat tube. Others may measure from center to center, bottom to center, or some other angle.

Also, not all frames have the same geometry. All of this means that a 21-inch frame from one company may fit very differently than the same size from another manufacturer.

Reach

Finding the right reach (the distance from the seat to the handlebars) is important for both comfort and control

As a rule of thumb, when you sit on the seat with your feet on the pedals and your hands on the handlebars, the handlebars should block your view of the front hub. You shouldn't be stretched out like Superman or sitting upright.

Be sure you have at least a slight bend in your elbows no matter what style of bike you choose

Locked elbows (caused by too-long reach) are a frequent cause of shoulder, neck and back pain

If you feel scrunched up and your elbows are in your ribs, the reach is too short

If the top tube is slightly too long or short, reach can usually be adjusted by changing the stem length - the stem being the part that connects the handlebars to the steering tube

Tires greatly influence a bike's riding characteristics, since they directly affect traction, steering and braking. There are two basic types of tires clincher and tubular.

Clincher

Refers to a conventional bike tire with a separate inner tube

When inflated, the tire clinches the rim as its inner edges, called the bead, become captured against the rim walls

Most road and all mountain, BMX and freestyle tires are clincher

Tubular (or sew-up)

Refer to a tube that is sewn into the tire, and then the tire is glued onto a special edgeless rim

These are only used for high-end road racing bikes

Tires for road and hybrid bikes

High-performance tires

High-performance tires are lightweight, narrow and can be inflated to high pressures (90 to 100 pounds or more)

They usually have a dual tread consisting of a firm center for low rolling resistance, flanked by a softer compound for good traction in turns

Recreational tires

Recreational tires are designed for durability and comfort

They're heavier than performance tires, but usually last longer

Mountain bikes

Knobby treads

Knobby treads are aggressive, designed to dig into loose soil. They are usually designed specifically for front and back wheels.

Widely spaced

Widely spaced knobs are best in wet terrain because they limit mud accumulation

Tightly spaced

Tightly spaced knobs are better in drier conditions. Neither is ideal for riding on pavement.

Semi-slick or bald tires

Semi-slick or bald tires have knobs on both edges for gripping in turns, but the center section has very little tread to allow for faster straight-on riding. They are good on dry, packed dirt trails and roads.

Hybrid treads

Hybrid treads are cut into the tire rather than protruding like knobs. They are good for pavement, dirt roads and hard-packed trails.

Slick tires

Slick tires have no tread, and are designed to be ridden only on pavement

Kevlar tires

If you will be riding on city streets or in places where you may encounter debris, consider investing in kevlar tires

They are a bit more expensive than traditional tires, but could save you money and aggravation in the long run if you suffer from frequent flats and punctures